Sulfur/phosphorus co-doping sequence – unlocking the key to performance enhancement of NiFe(OH)x catalyst in overall water splitting

Water splitting is a key and efficient method for hydrogen production. A major hurdle in overall water decomposition is developing affordable, highly active electrocatalysts to boost hydrogen (HER) and oxygen (OER) evolution reactions. In this work, influence of sulfur/ phosphorus co-doping sequence on the performance of NiFe(OH) x catalyst on the surface of nickel foam (NF) for overall water splitting was investigated. The findings of the experiment indicate that NiFe 0.4 P 1.2 S 1.6 /NF exhibits an overpotential of 67 mV for HER and 106 mV for OER at 10 mA cm −2 . Additionally, the Tafel slopes are reported as 60.92 mV dec -1 and 18.87 mV dec -1 , correspondingly. Electrochemical impedance spectroscopy reveals that NiFe 0.4 P 1.2 S 1.6 /NF exhibits low R ct values: 0.88 Ω for HER and 2.58 Ω for OER. Furthermore, its electrochemical active surface areas measure 303.8 cm 2 (HER) and 121.25 cm 2 (OER). Stability and i-t curve tests confirm the robustness of NiFe 0 . 4 P 1 . 2 S 1 . 6 /NF in HER (86.43 % retention) and OER (75.07 % retention) over 10-hour durability tests, maintaining ∼ 87.11 % initial cell voltage. This sulfur-phosphorus codoping method presents a new strategy for efficient HER/OER electrocatalysts.